Augmented Reality!

Wikipedia says it is a field of computer research which deals with the combination of real world and computer generated data, the great thing is that anyone with a regular cameraphone (and the required software) can take advantage of this technology. The end-user can in real time see the virtual and real environment interact.
While it is not new to integrate 3d elements in a scene or vice-versa, which can be achieved using any 3d or compositing application, in this case, this can be done on the spot, in real-time, the end goal being the interaction with the environment, not simply a static rendering of a composite 2d-3d scene. it is more of a 3d real -3d virtual real-time composition.

An amazing video can be seen here, it depicts a table tennis game, the integration of a virtual element in a real environment and the interaction with virtual elements within a real environment

Applications:
-Interior design and architecture
-Virtual sets
-Furniture vendors like IKEA: a customer would be able just by uploading data on his cameraphone, to see how the furniture he is about to by would fit in his appartment.

From Tommy's s60 Blog